$seen->{ ref($_) ? $_ : \$_} = undef

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You are aware that ref can return a false value even if its argument is a reference? 

$ perl -wle 'print ref bless [] => 0'
0

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You ought to check for definedness, which is easy in 5.8.1 with the defined-or patch: 

$seen -> {ref () // \$_} = undef;

[download]

Abigail

In reply to Re: Recursive map Design Questions by Abigail-II
in thread Recursive map Design Questions by bsb

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